Stabilized phonograph arm



Oct. 5, 1943. A. M. JONES K STABILIZED PHONOGRAPH ARM 2 Sheets-sheet 1'Filed Dec. ll, 14940 Oct. 5, l943. A. M. JONES 2,331,122

STABILIZED PHoNoGRAPH ARM `Filed De'c. 11, '1940 2 Sheets-Sheet 2afwaaiented Oct. 5, 1943 UNITED STATES PATENT oFFIcE ApplicationDecember 11, 1940, Serial No. 369,643

2 Claims.

This invention relates to a phonographic, re-

producing and recording apparatus, and the like,

masses and counterrotating masses, the pressure at the stylus beingobtained by means of tension between the parts of the phonograph armrather than the force of gravity; thus, movement of the phonograph willnot tend to cause the arm to move and change its pressure or directionof pressure at the stylus, eliminating the condition known as jumpingstylus.

A further object of this invention is the production of a pick-up armwhich is simple in construction, may be manufactured commerciallyeconomically, and which may be designed to use the same essential partsas pick-ups of presentday manufacture.

A still further object of this invention is the production of a pick-uparm which is so foolproof and so similar in operation to the ones usedin ordinary sound work, that re-education in its use will beunnecessary.

Other objects and advantages of the present invention will appearthroughout the following specification and claims.

In the drawings: Figure 1 is a side elevational view of one form of myimproved phonograph arm, certain parts being shown in section;

Figure l-A is an optional form of Figure 1;

Figure 2 is a vertical sectional view taken on line 2,-2 of Figure 1;

Figure 3 is a horizontal sectional view taken online 3 3- of Figure 1; l

Figure 4 is an enlarged vertical sectional view of the supporting post,a part of the arm and other associated parts;

Figure 5 is a perspective view of the tension means: engaging plate;

Figure 6 is a perspective view of the journal platefor the phonographarm;

Figure 7 is a perspective view of the lower locking plate for thetension means `oi the phonograph arm;

Figure 8 is a perspective view of the lower end of the tension screw;

Figure 9 is a side elevational view of a modified form of phonographarm, certain parts being shown in section;

Figure 9-A is an optional form of Figure 9;

Figure 9-B is a front end view of Figure 9, with an yadded optionalmeans for holding the arm igid vertically with respect to abuttingrecord;

Figure 10 is a top plan view of the phonograph arm and record associatedtherewith;

Figure 1l is a longitudinal fragmentary sectional view showing a furthermodified form of tension means for the phonograph arm;

Figure 12 is a longitudinal fragmentary sectional view of a stillfurther modied form of tension means for the phonograph arm;

Figure 13 is a vertical sectional view showing a form of the means forresisting lateral swing of the phonograph arm;

Figures 14 and 15 are vertical sectional views similar to Figure 13,showing further modiiled forms;

l Figure 16 is a top plan view of a modified shock-resisting means forcarrying a pick-up head; l

Figure 17 is a perspective view of a means for holding the outer end ofa phonograph arm and Figure 18 is a vertical sectional view showingV amodifled form of the means for resisting lateral swing of the phonographarm.

By referring to the drawings, it will be seen that 20 designates apick-up arm which may be formed of light metal or molded plastics, the

pick-up arm 20 being preferably hollow along its under face andconstituting a substantially U- shaped structure in cross section. Acrystal or pick-up head 2| is carried by the outer end of the pick-uparm 20, as shown in Figure 3. A counter-balance 22 is carried bythe rearor opposite end of the Dick-up arm 20 with respect to the crystal orpick-up head 2|, so that both the lateral and vertical pivots oi' thearm are at its center of gravity. 'I'he arm should be reasonably lshortand light in weight.

A pick-up arm supporting standard 23 is carried by a suitable mountingboard 24 and this standard 23 extends in a vertical position, as shownin Figures 1 and 4. A tension adjusting screw 25 'is carried by thepick-up arm 20 adjacent the counterf-balance 22 and this tensionadjusting screw' 25 is provided with a thumb head 28 (attached by atight tting pin z-a) which extends above the arm 2|) to facilitate theoperation of the screw 25. This screw carries a square-shaped nut or cap21 upon the threaded portion ofthe screw 25, which threaded portionpreferably extends about one-half of the length of the screw 25. Itshould be noted that square nut 21 is adapted to rest against the frontface of the counter-balance 22 to prevent the nut 21 from rotating as itis threaded by screw 25 to an adjusting position. A locking plate 28 iscarried by the bottom of the counter-balance 22 and this locking plateis provided with a toothed portion 29 upon its under face which isengaged by a toothed portion 30 carried by the lower end of the screw 25to hold the screw 25 in a set position. A compression coil spring'3l iscarried by the screw 25 and rests against the nut 21 at its upper end.The lower end of the spring 3| rests upon the rearwardly extendingportion 32 of the tension control plate 33, the lower end of the screw25 passing through the elongated slot. 34 in the rearwardly extendingportion 32 of the tension control plate 33. The tension'control plate 33is fixed upon the upper end of the standard 23, the tension' controlplate 33 having a forwardly extending end 35 terminating in an upwardlyextending lip 36. This end has an aperture 31 formed therein.

A vertically extending hollow tube 38 extends through the centralaperture 33 of the tension control plate 33, and this plate 33 supportsa rubber washer 40. This rubber washer in turn supports a metal journalplate 4| the journal plate 4| having a projecting tongue 42 which fitswithin the aperture 31 of the tension control plate 33 to prevent itsrotating. The hole of plate 4| is somewhat larger than tube 38. Thisjournal plate 4I in turn supports a rubber washer 43 and a metal washer44 is carried by the Washer 43. The ends of the tube 38 are outturned toprovide a securing ferrule to hold the vibration damping assemblytogether, the vibration damping assembly comprising the plates- 33 and4| and the washers 40, 43 and 44. The wires 45 leading to the pick-uphead pass through this tube 38, as shown in Figure 4. 'I'he journalplate 4| is pro- Figure l-a is an optional design of Figure l in whichthe arm 2lia is balanced for vertical movement at 48-a forward of thepivot of its standard 23--a allowing lateral movement. This design hasthe advantage of permitting the standard to be used further to the rearof the arm with a smaller weight '.2-a on the'. arm. The latter weight22-a is smaller because it isfurther to the rear of pivot 26-a. The armmust be balanced about its standard 'Z3-a by means of an added weight 85attached opposite the arm 20-a to its standard 23-a. This arm will haveless inertia in a vertical plane, but more when rotating laterally.

By referring to Figure 9 it will be seen that a modied form of theinvention is illustrated wherein a pick-up arm 2lib is shown having acounter-balance weight 22-b at its rear end. A tension control plate33-a is supported upon the standard 23-b in a manner similar to thatpreviously described with respect to Figure 1. A journal plate 4|-a iscarried by a vibration damping assembly 43--a similar to that illus-`trated in Figure 1. In the structure shown in Figure 9, however, atension spring is carried by a suspended pin 6| which pin is supportedby the arm 2li-b, the lower end of the pin sliding through a round holein the rearwardly extending portion 32-a of the tension. control plate33-a.

This plate 33--a is provided with a forwardly extending tongue62 whichcarries a vertically extending adjusting screw 83, the screw'83contacting a cushioned washer 64 which abuts the under face of the arm2li-b, in all providing a stop for the pick-up arm 2lib adjustable tothe turntable height and holding the arm 20--b rigid with respect tostandard 23--b during operation.

vided with laterally extending journal portions 48 which are journaledin the sides of the pickup arm 20, as shown in Figure 3.

The standard 23 is supported upon the upper threaded end of a hollowsleeve 41 and the lower end of this-sleeve carries a tap or n ut 4 8-a.The sleeve 41 passes through the mounting board 24 and extends through athimble 48 which also passes through the board 24. as shown in Figure 4.Shock absorbing washers formed of rubber or other material 49 and 50 arecarried by the thimble 48 and engage the mounting board 24. Aball-bearing race 5| may be carried by the stand.- ard 23. as shown. Acompression spring 52 is carried by the lower end of the hollow sleeve41 and abuts against a washer 53. the washer 53 engaging a nut 54, whichnut 54 is threaded on the lower end of the hollow sleeve 41. 'I'hepickup wire passes down through the standard 23 and the hollow sleeve41.

'I'he pick-up arm 20 and its component parts including the adjustingspring 3|, are perfectly balanced on the laterally extending journals46. and on the vertical axis of the arm. 'I'he shaft 23 with itscomponent parts. comprising the vibration damping assembly, is alsoperfectly balanced independently about its axis. In other words; allpivots are at the centers of gravity of the parts which are adapted topivot about them.

Standard 23-b is mounted on board 24-b through a ball-bearing pivot asin Figure 1.

The outer end of pick-up arm 20--b carries a hanger 11 interposedbetween cushion washers 13 and 14 and metal Washer 18. 'I'heconstruction and operation of this vibration damping hanger is verysimilar in construction and operation to the vibration damping assemblydescribed in Figure 4. This U-shaped hanger 11 pivotally supports apick-up head 19 at its center of gravity. A iiat spring 80 is secured tothe under face of arm 20 and is slidably mounted through a suitableguide 8| so that there will be an even upward tension on the guide 8|for any position oi' the pick-up head 19. The tension on the spring 8Uis adjusted by increasing or decreasing its length by means of aslidably mounted guide 12 through which spring feeds. This guide isfrictionally held in a slot on the top of the arm 20-b. In order thatthe inertia of the head 18 will not cause a change in pressure at thestylus when subj ected to movement in a straight line, the pick-up headis shown mounted in its center oi gravity. So that the needle will befree to move up and down with undulations of the record and slightmovement of the pick-up arm with respect to the turntable due tovibration of these parts, the head is pivoted so that the needle movesin an arc substantially perpendicular to the face of the record;otherwise, a force directed at the needle would tend to push against thepivot, which does not yield. In other words, the pivot of the headshould be as low to the record and as far back from the needle aspracticable. Relatively small inertia of the head 13 as compared withthe tension upon it also allows this unrestricted vertical movement.'I'he tension means 88 should direct a force substantially perpendicularto a plane running through its point of contact and the.

axis of the head; otherwise, it likewise will pull against the pivot`rather than cause rotation about it. 'I'he tension means should consistof a reasonably long spring so that the tension will not be diierent forthe varying positions of the pickup head. In order to accomplish all ofthe above an elongated head such as is shown should be` used. Crystalheads are universally constructed.

relying solely on the other one, abutting the standard. Of course,either or both vibration damping assemblies may be omitted. and bothwould hardly be necessary.

In this arm` likewise as in the one of Figure 1. all pivots are at thecenters of gravity of the parts which are collectively adapted to moveabout them lduring operation. v

In association with the larm 28-b a stop pin 15 is properly located uponthe mounting" board 24--b and a supporting yoke 16 is also properlylocated to receive the arm 'Z8-b. The pick-up arm 28--b may be in theshape shown in Figure 10, if desired.

Figure 9-a shows an optional design of the arm of Figure 9 in which thearm is hinged at 66 to 'allow part 28c| to be lifted oil the record,either for changing needles or for changing records. In order to removethe arm for purposes of changing records, the pick-up head as shown inFigure 9 permits enough vertical movement so that the arm may belaterally moved aside without necessitating verticalA removal-of the armitself, so hinging of the arm is not absolutely necessary especiallywhere permanent needles are used. Part 28--c-2 is the other half of thearm and is connected to standard 23--c by means of a wing nut 69 whichlocks it in any vertical position desired. Parts 28--c-I and 28\c-'2 arelocked rigidly together by hook 61.- The entire unit is balanced aboutthe axis of the standard 23c by means of weight 65-a attached to thestandard at the rear of arm 28-c.

Figure 9-b is a front-end view of Figure 9 with an added optional meansfor holding the arm stationary -vertically with respect to an abuttingrecord. Part 18 is a rigid and smoothly finished piece of metal abuttingthe record immediately to the rear of the stylus and secured to arm2li-d. The stopscrew 63 of Figure 9 is of course adjusted so that thetension of spring 68 acts against stop 18 instead of stop 63. Crystal19-a is of course yieldably mounted as in Figure 9. Stop 18 is Figures 1and 9. In this instance as shown in Figure 11, the standard 23-dsupports a vibration damping assembly 82 somewhat similar to 4thatdescribed with respect to Figures 1 and 9.

In the structure shown in Figure 11, however, a tension plate 83 iscarried by the -vibration damping assembly 82 and is provided with aforwardly extending flat spring 84 which contacts a transverse pin 8 5carried by the arm 28--e. A journal plate 86 is carried by the vibration.damping assembly 82 and is provided with a rearwardly extending tongue81 which extends through the uptumed apertured ear 88 of the tensionplate 83.

The journal plate 86 is provided with laterally extending journals 89which provide apivot for vertical movement of the pick-up arm 28-e.

In Figure 12 there is illustrated a further modiiled formvwherein thepick-up arm 28-f is pivotally supported upon a vibration dampingassembly 82a through the medium of the journais 89-a. A" tension plate98 is supported upon the standard 23-e and this tension plate carries aweighted portion 9| (adapted to balance the forwardly extending tongue93 of the journal plate which carries the journals 89va. An adjustabletension bolt 94 is suspended from the arm 28f and extends through a`slot in the forwardly extending end 95 of the tension plate 90. Asetscrew 96 is carriedby the end 95 and engages a cushion washer 91providing an adjustable vertical stop for the arm 28--f. In this pick-updesign as well as all the others all pivots are at ythe centers ofgravity of the yparts adapted to move about them.

In Figure 13 there is shown a form of the invention wherein the standard23-1 is rotatably mounted through a thimble 1| carried by the mountingboard 24-d. A gear 98 is carried by the lower end of the standard 23--fand meshes with a pinion 99 supporting a'ywheel |88, this wheel beingjournaled upon a hanger |8| of suitable type. The flywheel is weightedand geared so that its moment of inertia about its axis is exactly equaland opposite to that of the -entire pick-up assembly about its verticalaxis made to have as little frictional resistance as posresisted by thestop 18. In Figure 9 the force is exerted on stop 63 rather than on thestylus. The stop of Figure 9-b is desirable for use with automaticrecord changers where several records are on the turntable at a time, asit will automatically adjust itself toA varying turntable heights,whereas that of Figure 9 will not. When any of the foregoing devices areused with automatic record changers, any added engaging parts should becounterbalanced'about their axes.

In Figure 11 there is shown a modified type of the invention wherein thepick-up arm 28-e is supported in a manner somewhat similar to thatillustrated and described with respect to exactly counteracting anytendency for the bal' anced pick-up arm to rotate in a lateral plane dueto its inertia when subjected to rotation.

In Figure 14 there is shown a modified form of the invention wherein themounting board 24--e carries a thimble 1 |-a through which extends apick-up arm supporting standard 23-g. This standard 23- g carries abevel gear |82 which is secured thereto, and the standard 23-g alsosupports a freely rotating flywheel |83 at its llower end. The flywheel|83 carries a gear portion |84 near its center and an idle pinion |85meshes with the gear |82, and the gear portion |84, the' idle pinion |05being supported upon the hanger bracket |86. Likewise this wheel |83 isWeighted so thatits inertia. exactly opposes that of the pick-upassembly about the axis of its standard 23-g.

In Figure 15 there is shown a further modiiled form of the inventionillustrating a mounting board 24-f which supports a standard 23-h uponwhich is iixedly secured a iiywheel |81. A nger |98 extends laterallyfrom the standard 23--h and engages a vertical rod |89 which is pivotedupon a hanger bracket I|8. The lower end of the rod |89 extends throughslotted aperture Hl formed in the flywheel |81, and this mechanism alsoopposes the pick-ups moment of inertia about the axis of the standard23-h.

In Figures 13, 14 and 15, a ywheel is shown as being the mostpracticable rotating mass to be'used. However, any shaped mass pivotedat its center of gravity would be satisfactory. As the counter-rotatingmasses of Figures 14 and 15 rotate about the same axis as the pick-uparm they are scientically perfect; however, for practical purposes the`construction shown in Figure 13 with an independent axis for the ywheel'will be entirely satisfactory for all practical purposes. Lever meansinstead of gears may be used in- Figure 13. These fiywheels illustratedin Figures 13, 14 and 15, which are. geared or engaged so that theirmoments of inertia are exactly equal to and will oppose that o1 thepick-up arm rotating in a horizontal plane, have a dual purpose: (1)They eliminate any tendency for the pick-up arm to rotate in ahorizonta1 plane with respect to its support when the support issubjected to rotating movement, while at the same time free lateralmovement of the arm is permitted to follow the feed of a record; and (2)the inertia of a mass in equilibrium will also hinder any lateralvibration from any cause whatsoever, being set up in the laterallyengaged pick-up arm.

Figure 16 is a top plan view of a modie'd shock-resisting means forcarrying a pick-up head. |29 is a bar which is vdisposed laterallyacross the approximate center of a record by means of pivot |28 andlatch |21. Pulley wheels |23 are pivoted at either end of bar |29 andengage an endless string |26. Freely moving slides |24 and |25 on bar|29 are attached to string I 2G, eachI at an opposite side of bar |29and equally distant from the pulleys |23. Slide |25 is a pick-upcarrying slide and carries a yieldably mounted'pick-up head such asillustrated at the extremity of the arm of Figure 9. Slide |24 is aweight carrying slide which is weighted so that its mass is exactlyequal to the mass of |25 and attached parts. This device is a modiiiedmeans of having a pick-up engaged with an equal mass moving oppositelywith it in the same plane. The same is done in Figures `1 and 9;however, here the inertia of `the device may be much smaller andvertical movement of the entire device is impossible during operation.Latch |21 permits removal of the arm off the record for changingrecords.

In Figure 17 there is shown-a further modified form of the inventionwherein the pick-up arm ||1 is illustrated, and this arm is engaged byan overhanging frame |8 which is provided with a felt or other frictionstrip ||9 on its lower face for frictiohally engaging the upper face ofthe pick-up arm ||1, preventing vertical movement of the arm andfrictionally resisting sudden lateral movement. The frame ||8 ispivoted, as at |20, to a suitable support, and stop pins |2|, preferablyadjustable, are suitably located to limit the downward swing of theframe ||8. Coil springs |22 are anchored at one end and secured at theother end to the inner face of the frame ||8near the forward end thereofbeyond the pivots |20, to hold the frame in contacting relation with thepick-up arm ||1. When the frame 8 is raised, however, to cause thespring connection |22 to be raised above the pivot |20 the springs |22will hold the frame ln an inoperative position out of contact with thepick-up arm H1. The pick-up arm shown is preferably mounted on pivots atits center of gravity and pressure at the needle point is obtainedbetween the overlying bar ||8 and the pick-up arm itself by pressure inthe frictional substance.

Figure 18 is a vertical sectional view showing a modified form forfrictionally resisting lateral rotation of a phonograph arm.'I'hestandard 23-i has attached to it a metal washer |31. Standard 23-ifits through a thimble 1|-b, which thimble is secured to mounting board24-g. Frictional substance such as felt |30 is interposed between washer|31 and thimble 1 |b. Washer |34 carried by standard 23-1 abuts thimble1|b and washer |30 on 23- abuts nut |38. Compression spring |38 isinterposed between these two washers, causing a tension in thetrictional substance |30. Nut |38 is threaded for adjustment so that thetension in the frictional substance |30 may be changed as desired.

In the modified forms of this invention an attempt has been made torender the inertia of the device ineffective in causing a change ofpressure at the stylus when the device is subjected toy change 0fposition. Any mass has inertia and tends when at rest to remain so andwhen'in motion to continue in motion in the same straight line ordirection, unless acted upon by some external force. There are fourpossible kinds of movement which a mass may be subiected to and willtend to resist. They are: (1) rotation in a horizontal plane, (2)rotationin a vertical plane, (3) movement in a straight line vertically,and (4) movement in a straight line horizontally. As an example to pointout how these movements are encountered in an ordinary vehicle, it willbe shown how .they come into play in an automobile and then how themodified forms are adapted to overcome them.

The most severe changes of position which an automobile is subjected toare non-rotational, such as stopping and starting, sudden movement upand down hills or bumps, and movement from the straight path whenturning a, curve, especial- 1y at high speeds (centrifugal force). Nextin importance is rotational movement in a vertical plane. This isencountered when the car noses up or down hills or bumps, with one endof the car going up or down with respect to the other, and is apt to besudden. Least in importance or severity is rotation in a horizontalplane. This would only be encountered severely when a car breaks into askid, one end of the car moving sidewise more than another. It would beencountered also in turning curves, but would not be sudden. When it isconsidered the time that it takes to make a complete U-turn and thesteady amount of force that it takes to completely rotate an object suchas the device used in this invention during that same period of time, itwill be seen that rotational movement encountered on curves is not agreat factor under ordinary driving conditions in producing a force onthe needle of a pick-up arm.

The device illustrated in Figure 1 has its lateral and vertical pivotsat its center of gravity. In other words, the masses of the arm areequal on all sides of the pivots; thus, it is impossible for straightmovement in any direction to tend to make this arm rotate about eitherof its axes. As this arm is affected by rotational movement it wasadvised in the specications to keep its moment of inertia about its axeslow, using lightweight parts in a reasonably short arm. It helps to putas many parts as possible, such as the spring tension assembly, to therear of the axes Aso that they will aid in counterbalancing rather thanhaving to be counterbalanced.

The pick-up illustrated in Figure 9 also 'has all of its parts balancedabout its axes so that direct movement of the phonograph is ineffectivein causing the arm or parts to rotate. To overcome the inertia of thearm and movement in a vertical plane, the great mass oi the arm is heldrigid, allowing vertical movement only in the pick-up head or sound boxwhich has such a small m`assl that its inertia when pivoted at itscenter of gravity is practically negligible. This prevents the pick-uphead digging in or Jumping out of the groove when vertical rotation ofthe vehicle is encountered as explained above on jolts or in starting upor down'hills. The pick-up head, due to its construction described inthe speciilcations with reference to Figure 9, is free to move up anddown without a change in pressure at the stylus to follow theundulations of an uneven record or to accommodate small variation of thespace between the pick-up arm and the tum-table due to vibration ofthese parts when subjected to shock and movement.

There is only one type of movement left which must be overcome, and thatis rotation in a horizontal plane.

a horizontal plane and engaged with the pick-up so that its moment of,inertia about its axis is equal and opposite to that of the pick-up.When this unit is attached to a phonograph and the phonograph is twistedor rotated in a horizontal plane, the pick-up arm will not be free toremain still with the phonograph revolving beneath it; and the entireunit will rotate together. When the counter-rotating means of Figures13, 14 and 15- is used in connection with Figure 9, each of the fourmovements to which a phonograph may be subjected is overcome.

A stabilized arm such as has been described in this invention may beused not only with sound transmission equipment but any other equipmentwhere necessary that it be free to move in a manner similar to aphonograph reproducing or recording head and yet be held in a state orequilibrium with respectto its support when movement oi' the support isencountered.

This is accomplished by using a mass rotating counter to that of thepick-up in trains and other vehicles or places where sudden movements,shocks and vibrationsare encountered, such as would render ordinarypick-ups useless. In an automobile, permanent installation may be madeby installing the pick-up, connected `to play through the radio, intheglove compartment, using a spring-driven or 6volt electric motor forturning records. Portable phonographs orradio-phonograph combinationsare frequently taken along in automobiles and other vehicles duringtrips, and when equipped with.the stabilized pick-up arm may still beused while the vehicle is in motion. In passenger vehicles when radioprograms are undesirable or cannot be received, considerable pleasurewill be afforded through the use of phonographs.

Passenger transportation companies, advertis'ers, scientists, the ArmySignal'Corps, and others, could use to advantage the pick-up armdescribed in this invention.

Havngdescribed the invention, what I claim as new is:

1. A device of the class described comprising a' supporting standard, apick-up arm carried by the supporting standard, a weight pivoted at itscenter of gravity and geared to said standard to rotate in an oppositedirection to the pick-up arm and mounted to rotate in a plane parallelwith the swing of the pick-up arm.

2. A device lof the class described comprising a pick-up arm mounted torotate about a pivot at its center of gravity, a weight pivoted-at itscen.- ter of gravity to rotate in a plane parallel to the movement ofthe pick-up arm, and connecting means for rotating the weight counter tothe rotation of the pick-up arm.

ALLEN MONROE JONES.

